Replication Data for: Environmental Protection Agency (EPA) National Air Toxics Assessment (NATA), 1996 - 2019 plus some 2020 AirToxScreen

Environmental Protection Agency (EPA) National Air Toxics Assessment (NATA), 1996 - 2019 plus some 2020 AirToxScreen.  1996, 1999, 2002, 2005, 2011, 2014, 2017, 2018, 2019, 2020.  For 2017 onward, the program changed to AirToxScreen, so the data for those years are technically AirToxScreen, but the format is still the same.  Each year the results can be categorized by state, and most years allow categorization by county or by Census Tract (from that year).  All years also can be categorized by pollutant - in these archives the only year that has files by pollutant is for 2011 (this description will be updated when those additional data can be added for additional years).  For full 2020 AirToxScreen data, see https://www.epa.gov/AirToxScreen/2020-airtoxscreen-assessment-results (accessed 9/23/2025).

2019

About the 2019 Assessment

This page provides the emissions data, ambient concentrations and health-effect results for the 2019 Air Toxics Screening Assessment, or AirToxScreen. You can also find links to supporting files and web pages with more information about these results.

EPA developed AirToxScreen as a screening tool for state, local and tribal air agencies. AirToxScreen’s results help these agencies identify which pollutants, emission sources and places they may wish to study further to better understand any possible risks to public health from air toxics. Often, more localized studies are needed to better characterize local-level risk. These studies often include air monitoring and more detailed modeling. 

The following files will help you navigate the AirToxScreen results:

• AirToxScreen Technical Support Document provides technical information on the assessment, including and emissions, modeling, and risk calculations. We've also included a folder containing supplemental data files referred to in the TSD and a document describing how we calculated ethylene oxide emissions from commercial sterilizers for this assessment.
• AirToxScreen Risk Drivers: pollutants that contribute most to risks and hazards.
• 2019 AirToxScreen: Emissions Update Document lists some of the known issues and updates that were not addressed during the review of the 2019 assessment, including information on some facilities about which EPA is aware that have reduced emissions of certain air toxics since 2019.
• AirToxScreen: Explanation of Data Elements provides descriptions of the many fields in the results files of AirToxScreen.

2018

About the 2018 Assessment

This page provides the emissions data, ambient concentrations and health-effect results for the 2018 Air Toxics Screening Assessment, or AirToxScreen. You can also find links to supporting files and web pages with more information about these results.

EPA developed AirToxScreen as a screening tool for state, local and tribal air agencies. AirToxScreen’s results help these agencies identify which pollutants, emission sources and places they may wish to study further to better understand any possible risks to public health from air toxics. Often, more localized studies are needed to better characterize local-level risk. These studies often include air monitoring and more detailed modeling. 

The following files will help you navigate the AirToxScreen results:

• AirToxScreen Technical Support Document provides technical information on the assessment, including and emissions, modeling, and risk calculations. We've also included a folder containing supplemental data files referred to in the TSD and a document describing how we calculated ethylene oxide emissions from commercial sterilizers for this assessment.
• AirToxScreen Risk Drivers for 2018: pollutants that contribute most to risks and hazards.
• 2018 AirToxScreen: Emissions Update Document lists some of the known issues and updates that were not addressed during the review of the 2018 assessment, including information on some facilities about which EPA is aware that have reduced emissions of certain air toxics since 2018.
• AirToxScreen: Explanation of Data Elements provides descriptions of the many fields in the results files of AirToxScreen.

2017

About the 2017 Assessment

This page provides the emissions data, ambient concentrations and health-effect results for the 2017 Air Toxics Screening Assessment, or AirToxScreen. You can also find links to supporting files and web pages with more information about these results.

EPA developed AirToxScreen as a screening tool for state, local and tribal air agencies. AirToxScreen’s results help these agencies identify which pollutants, emission sources and places they may wish to study further to better understand any possible risks to public health from air toxics. Often, more localized studies are needed to better characterize local-level risk. These studies often include air monitoring and more detailed modeling. 

The following files will help you navigate the AirToxScreen results:

• 2017 AirToxScreen: Technical Support Document provides technical information on the assessment, including and emissions, modeling, and risk calculations. We've also included a folder containing supplemental data files referred to in the TSD and a document describing how we calculated ethylene oxide emissions from commercial sterilizers for this assessment.
• 2017 AirToxScreen: Emissions Update Document lists some of the known issues and updates that were not addressed during the review of the 2017 assessment, including information on some facilities about which EPA is aware that have reduced emissions of certain air toxics since 2017.
• 2017 AirToxScreen: Explanation of Data Elements provides descriptions of the many fields in the results files of AirToxScreen.

2014

About the 2014 Assessment

This page provides the emissions data, ambient concentrations and health-effect results for the 2014 National Air Toxics Assessment. You can also find links to supporting files and web pages with more information about these results.

EPA developed NATA as a screening tool for state, local and tribal air agencies. NATA’s results help these agencies identify which pollutants, emission sources and places they may wish to study further to better understand any possible risks to public health from air toxics. Often, more localized studies are needed to better characterize local-level risk. These studies often include air monitoring and more detailed modeling. 

The following files will help you navigate the NATA results:

• 2014 NATA Results Summary
• 2014 NATA Technical Support Document provides technical information on the 2014 NATA, including and emissions, modeling, and risk calculations.
• 2014 NATA Emissions Update Document lists some of the known issues and updates that were not addressed during the review of the 2014 NATA.
• Explanation of Data Elements in 2014 NATA Results Tables provides descriptions of the many fields in the results files of the 2014 NATA.

2011

About the 2011 Assessment

This page provides the inventory inputs, ambient and exposure concentrations, and results for the 2011 National-scale Air Toxics Assessments.  There are also links to supporting files and web pages. EPA suggests that the results of this assessment be used cautiously, as the overall quality and uncertainties of the assessment will vary from location to location as well as from pollutant to pollutant.  In many cases more localized assessments, including monitoring and modeling, may be needed to better characterize local-level risk.

The following files will assist in navigating the results of this assessment:

• 2011 NATA Technical Support Document provides more information on the 2011 NATA emissions.
• 2011 NATA Errata and Emissions Update Sheet provides a list of some of the known issues and updates that were not addressed during the review of the 2011 NATA.
• Explanation of Data Elements in 2011 NATA Results Tables provides descriptions of the many fields in the results files of the 2011 NATA

2005

2005 State-specific NATA Emissions

The National Emissions Inventory (NEI) is EPA’s comprehensive, facility-specific emissions inventory database. It is used to support air quality modeling and other activities within the Air Toxics Program. For the 2005 NATA, the point source inventory used was developed by starting with the 2005 NEI.

The following PDF files may also be useful for understanding the 2005 NEI:

• Documentation for the 2005 Point Source National Emissions Inventory (pdf) (239.27 KB, September 9, 2010)  
• NEI Quality Assurance and Data Augmentation for Point Sources (pdf) (278.18 KB, February 1, 2006)

2002

In June 2009, EPA released the results of its 2002 national-scale assessment of air toxics emissions. The purpose of the national-scale assessment is to identify and prioritize air toxics, emission source types and locations which are of greatest potential concern in terms of contributing to population risk. EPA uses the results of these assessments in many ways, including:

• To work with communities in designing their own local-scale assessments,
• To set priorities for improving data in emissions inventories, and
• To help direct priorities for expanding and improving the network of air toxics monitoring.

The national-scale assessment modeled 180 of the 187 Clean Air Act air toxics (PDF) (3pp, 15k) plus diesel particulate matter (diesel PM). The assessment includes four steps that focus on the year 2002:

1. Compiling a national emissions inventory of air toxics emissions from outdoor sources
2. Estimating ambient concentrations of air toxics across the United States
3. Estimating population exposures across the United States
4. Characterizing potential public health risk due to inhalation of air toxics including both cancer and noncancer effects

For information summarizing the 2002 assessment, see the Fact Sheet and Summary of Results pages. The Summary of Results page also provides national maps of cancer and noncancer effects.

The emissions used in the current assessment are from the 2002 emission inventory which is the most complete and up-to-date available. Working with the states, EPA updates air toxics emission inventories every 3 years. The next national-scale assessment will focus on 2005 emissions and will be available in early 2011.

As part of EPA's National Air Toxics Assessment activities, EPA conducted its first national-scale assessment for the year 1996. That assessment included 33 air pollutants (a subset of 32 air toxics on the Clean Air Act's list of 187 air toxics plus diesel particulate matter (diesel PM). In February of 2006, EPA released the second of its NATA assessments. This assessment was based on emissions from the 1999 National Emission Inventory and included the assessment of 177 hazardous air toxics plus diesel particulate matter.

1999

In February 2006, EPA released the results of its national-scale assessment of 1999 air toxics emissions. The purpose of the national-scale assessment is to identify and prioritize air toxics, emission source types and locations which are of greatest potential concern in terms of contributing to population risk. EPA uses the results of these assessments in many ways, including:

• to work with communities in designing their own local-scale assessments,
• to set priorities for improving data in emissions inventories, and
• to help direct priorities for expanding and improving the network of air toxics monitoring.

The national-scale assessment includes 177 air pollutants (a subset of the air toxics on the Clean Air Act's list of 187 air toxics plus diesel particulate matter (diesel PM)). The assessment includes four steps that focus on the year 1999:

1. Compiling a national emissions inventory of air toxics emissions from outdoor sources.
2. Estimating ambient concentrations of air toxics across the United States.
3. Estimating population exposures across the United States.
4. Characterizing potential public health risk due to inhalation of air toxics including both cancer and noncancer effects.

For information summarizing the 1999 assessment, see the fact sheet

The data are from 1999 since emissions inventories from that year are the most complete and up-to-date available. Working with the states, EPA updates air toxics emissions inventories every 3 years. The next national-scale assessment will focus on the 2002 emissions inventory which was completed in December 2005.

1996

As part of EPA's National Air Toxics Assessment activities, EPA conducted a national-scale assessment of 33 air pollutants (a subset of 32 air toxics on the Clean Air Act's list of 188 air toxics plus diesel particulate matter (diesel PM)). The assessment includes four steps that look at the year 1996. Note: As of May 2002, the results posted for all four steps include revisions based on input from scientific peer review.

1. Compiling a national emissions inventory of air toxics emissions from outdoor sources. Available here
2. Estimating ambient concentrations of air toxics across the contiguous United States. Available here
3. Estimating population exposures across the contiguous United States. Available here
4. Characterizing potential public health risk due to inhalation of air toxics including both cancer and noncancer effects. Available here

The goal of the national-scale assessment is to identify those air toxics which are of greatest potential concern, in terms of contribution to population risk. The results will be used to set priorities for the collection of additional air toxics data (e.g., emissions data and ambient monitoring data).